Blenders are household devices often used to blend or mix drinks or liquids. On the other hand, food processors are household devices commonly used to chop, cut, slice, and/or mix various solid foods such as vegetables, fruits, or meats. Different blade designs and rotation speeds are used in a blender or a food processor in order to accomplish the mixing or cutting actions desired.
Conventional household blenders typically have a motor connected to a blade assembly, and the speed of the rotating blade or motor may be varied based on selections made by the user.
For example, U.S. Pat. No. 3,678,288 to Swanke et al. describes a blender having seven speed selection push buttons. The push-buttons drive slider elements that close switches so as to selectively energize various combinations of fields in a drive motor having multiple fields. Field selection provides seven speeds in a high range. Seven speeds in a low range are obtained by applying only half cycles of the AC energizing voltage to the motor when certain combinations of the switches are actuated. Once a speed selection push button is depressed, the motor is energized until an OFF switch is actuated. The device also has a jogger or pulse mode pushbutton that energizes the motor at one speed only as long as the pushbutton is depressed. Pulsing the motor on/off or at high and then low speeds permits the material being blended to fall back to the region of the cutting knives thereby improving the blending or mixing of the material.
U.S. Pat. No. 3,951,351 to Ernster et al. describes a blender having a rotary switch for selecting a high or low range of speeds and five pushbutton switches for selecting a speed within the selected range. The pushbutton switches connect various segments of the motor field winding in the energizing circuit. This device also includes a pulse mode pushbutton that causes energization of the motor only as long as the pushbutton is depressed. The motor may be energized in the pulse mode at any selected speed.
U.S. Pat. No. 3,548,280 to Cockroft describes a blender provided with 10 speed selection switches. A SCR is connected in series with the motor and has a control electrode connected to resistances that are brought into the electrode circuit by actuation of the speed selection switches to control the angle of firing of the SCR and thus the speed of the motor. This device also has a mode selection switch for selecting the manual mode or a cycling or pulse mode in which the motor is alternately energized and deenergized over a plurality of cycles, the number of cycles being set by a potentiometer controlled by a rotatable knob. In a preferred embodiment, the on and off intervals are set during manufacture but two potentiometers may be provided to enable an operator to vary the on and off times.
U.S. Pat. No. 5,347,205 to Piland describes a blender with a microcontroller for controlling energization of the blender drive motor. The speed of the motor is determined by a manual selection of N speed range selection switches, M speed selection switches, and a pulse mode switch.
Typically, the blade attachment in conventional blenders consists of two generally shaped blades, a top blade and a bottom blade, joined together at a central point with their respective ends oriented in opposite directions. Because of this blender blade design, conventional blenders usually are not able to successfully chop, slice, or cut solid food because solid food does not flow into the U-shaped blades without adding liquid. Although the solids may make some contact with the blades, typically at least some liquid must be added to the blender in order to successfully liquefy or cut the solid food into very small pieces.
Another drawback with blenders is the number of different operations that must be performed to successfully blend a mixture. Typically, to blend or mix items in a blender, a user will press a sequence of buttons on the blender. For example, to chop ice, a user may hit a slow button, wait a while, hit a faster speed, wait, hit yet a faster speed, etc. The user may have to stop the blending process to dislodge ice or to assure the ice is coming into contact with the blades. This process can be very frustrating, and with conventional blenders may still result in an unsatisfactory chopping or blending of the items in the blender.